Extreme pressure lubricant



'a lubricant which will 4 consisting of alkyl, chloralkyl,

Patented Jan. 5, 1943 UNITED STATES PATENT OFFICE 2,307,307 EXTREME PRESSURE LUBRICANT Bernard H. Shoemaker, Hammond, Ind., assignor to Standard Oil Company, Chicago, por'ation of Indiana 111., a cor- No Drawing. Application September 12, 1938,

Serial No. 229,523

11 Claims. (Cl. 252-46) Thi invention relates to improvements in lubricants, and in particular, to improvements in extreme pressure lubricants adapted for use on bearing surfaces which are subjected to high pressures and high rubbin velocities during use.

High unit pressures which are encountered frequently in devices employed for the transmission of power, such as hypoid gears, worm gears, heavy duty bearings, planetary automatic shifts and the like, necessitate the use of lubriproperties, which make them specially adapted for use under conditions of high pressure where the pressures encountered are of such magnitude that the separation of gear teeth or bearing surfaces by an ordinary oil film is not possible, are

known in the art as extreme pressure lubricants.

Extreme pressure lubricants are likewise important in cutting and drawing operations where the oil must withstand the high pressures encountered under those conditions of use.

It is an object of this invention to provide an improved extreme pressure lubricant which will 7 ive superior lubrication to bearing surfaces which are subjected to high' pressures and/or high rubbing velocities.

Another object of this invention is to provide ing failure from scoring or galling caused by the welding of small areas of th matting surfaces due to highpressure and high temperature.

I have found that the foregoing objects can be attained if small amounts, preferably from about 0.01% to about 2%, of thioketopolysulfides, of the type obtained by reacting an alkali-metal xanthate with a sulfur chloride, are added to lubricants, such as oils and greases. These comprevent gear teeth or bearpounds have the general formula (RXC=S)2S1|,

in which R is a radical selected from the group aryl and chloraryl radicals, X is an element selected from the group consisting of oxygen and sulfur, and n is an integer greater than 2.

These compounds may b prepared by reacting an alkali metal xanthate with a sulfur chloride. For example, the tetrathio derivative may be prepared by reacting twenty-eight grams of potassium ethyl xanthate, suspended in hexane, or any other suitable diluent, with a little less than the calculated required amount of S2012, and refluxing the reactants on a steam bath for about two hours. lieved to take place:

KS 2 C=S+SzCh (RO )aS4+2KCl To obtain the trithio derivatives the alkali metal xanthate i reacted with SCl2.

Because of the presence of the thio-keto group i in these compounds I have called them thioketopolysulfides, but more specificallyl believe them to be thioformate polysulfides, and while I refer to them hereinafteras thioformates, I do not wish to limit the scope of this inventionto thioformates, but to the reaction product of an alkalimetal xanthate and a sulfur chloride.

Specific examples of the type of compounds which I may use are the following:

Tetrathio diethylthioformate Tetrathio dibutylthioformate Tetrathio diamyldithioformate Tetrathio dilaurylthioformate Tetrathio dilauryl dithioformate Tetrathio dichlorbutylthioformate Tetrathio dichlorlauryldithioformate Tetrathio diphenylthioformate. Tetrathio dichlorphenyldithioformate Trithio dipropylthioformate Trithio dichlorbutylthioformate Trithio diphenylthioformate Trithio di-octyldithioformate The following reaction is beat Houston, Texas, November 1'7, 1932. Briefly, it consists of a test pin or journal made of A, inch diameter drill rod which can be rotated in a V2 inch long split bushing with provisions for loading the bearing thus formed by clamping together the two halves of the split bushing. Provision is also made to measure the torque required to rotate the journal in the loaded hear- The standard method of making a test on the Almen machine consists in immersing the test pin and bushings in the lubricant to be tested and then rotating the test pin at 600 R. P. M. The load, which clamps the two halves of the split bushing, is increased at the rate of 2 lbs. added every 10 seconds. A record is made of the torque required to rotate the pin at each load increment and the test is completed either when 30 lbs. have been added to the loading device or when seizure occurs, whichever happens first.

The following example will illustrate the effectiveness of the addition of small amounts of thioformate polysulfides in lubricating oils under extreme pressure conditions. A mineral lubricating oil having a viscosity of about 1'70 seconds at 130 F. and the same oil with 0.5% of tetrathio diethylthioformate when tested in the Almen testing machine gave the following results:

Load at which seizure occurred Pounds Pounds iii 30 Control 6 Control-+% tetrathio diothylthinformate. 30+

While I have described my invention with a specific embodiment thereof, it is to be understood that the same is merely illustrative of the invention and not a limitation thereof, except insofar as the same is defined in the appended claims,- which are to be interpreted as broadly as the prior art will permit.

1 claim:

1. An extreme pressure lubricant containing a lubricant and a thioketo polysulfide having the general formula (RXC=S) 2Sn. in which R is a radical selected from the group consisting of alkyl, chloralkyl, aryl and chloraryl radicals, X is an element selected from the group consisting of oxygen and sulfur and n is an integer greater than 2, said thioketo polysulfide being used in small but sufllcient quantities to impart extreme pressure properties to said lubricant.

2. An extreme pressure lubricant containing a than 2.

mineral lubricating oil and from about 0.01% to about 2% of a thloketo polysulfide having thean element selected from the group consisting of oxygen and sulfur and n is aninteger greater 3. An extreme pressure lubricant containing a mineral lubricating oil and from about 0.01% to about 2% of tetrathio diethylthioiormate.

4. An extreme pressure lubricant containing a lubricant and a thioketo polysulfide having the general formula (RXC=S)2S3 in which R is a radical selected from the group consisting of alkyl, chloralkyl, aryl and chloraryl radicals, and X is an element selected from the group consisting of oxygen and sulfur, being used in small but sufflcient quantity to impart extreme pressure properties to said lubricant.

5. An extreme pressure lubricant containing a lubricant and a thioketo polysulfide having-the general formula (RXC=S)2S4 in which R is a radical selected from the group consisting of alkyl, chloralkyl, aryl and chloraryl radicals, and X is an element selected from the group consisting of oxygen and sulfur, said thioketo polysulfide being used in small but sufiicient quantity to impart extreme pressure properties to said lubricant.

6. An extreme pressure lubricant containing a lubricant and a tetrathio alkyl thioformate in small but sufficient quantity to impart extreme pressure propertiesto said lubricant.

7. A lubricating composition comprising a lubricating oil base stock and at least .01% of a soluble xanthogen sulfide having the general formula:

R-X- (S) -XR where R and R are like or unlike alkyl or aryl radicals, and X is either oxygen or sulfur.

8. A composition of matter comprising an oil and a small amount of organic xanthogen tetra- 9. A lubricating composition comprising a mineral lubricating oil and at least about 0.01% of a soluble organic xanthogen tetrasulfide.

10. A lubricating composition according to claim 9 in which the tetrasulfide is an alkyl xanthogen tetrasulfide.

11. A ubricating composition according to claim 9 in which the tetrasulfide is ethyl xanthyltetrasulflde.

BERNARD H. SHOEMAKER.

consisting of said thioketo polysulfide'. 

